 The Gold Star. It's America's promise to never forget. During World War I, families displayed a blue star to recognize immediate family members serving in the U.S. military. If that family member was killed in combat, the blue star was replaced with a gold star. Today, the last Sunday of September is designated Gold Star Mothers and Families Day. To honor those loved ones who died in service to our country. This monument in the National Museum of the U.S. Air Force Memorial Park salutes those fallen family members and reminds us to never forget.